Comparison of spreader penetration and obturation density in curved canals

Objective: To compare the initial penetration depth of nickel-titanium(NiTi)and stainless-steel (SS) spreader during lateral compaction and the quality of the seal in curved canals. METHODS: Forty extracted mandibular premolars with a single canal were instrumented using a standardized rotary instrumentation technique and grouped by degree of curvature for comparison. NiTi and SS #25 spreaders were used to obturate the canals containing a master cone while the penetration depths were measured. Horizontal sections were cut 2 and 4mm from the apex and photographed under stereomicroscope. The area of the canal and gutta-percha in cross-sections was measured using an image analysis programme. RESULTS: NiTi spreaders penetrated to a significantly greater depth than SS spreaders (0.48mm vs 1.43mm )in canal curvatures greater than 20 degrees. No significant difference occurred in canal curvatures of 0 to 20 degrees. In canal curvatures greater than 20 degrees the levels of 2mm have significantly more gutta-percha fill with master cone using NiTi spreaders. At 4mm level there was no significant difference between two groups (P>0.05). CONCLUSION: The NiTi spreaders penetrated to a significantly greater depth than SS spreaders and more favorable apical seal in cured canals.